As this type damper, the followings have been hitherto suggested: (1) an adhesion type damper wherein a rubber elastic body is vulcanized and adhered between a sleeve and a inertia mass body and a hub is press-fitted inside the sleeve; (2) an adhesion type damper wherein, after an adhesive agent is applied to both surfaces of the a sleeve and a inertia mass body, a vulcanized and molded rubber elastic body is press-fitted between the hub and the inertia mass body; (3) an adhesion type damper obtained by filling non-vulcanized rubber between a hub and a inertia mass body and then vulcanizing and adhering this non-vulcanized rubber; (4) a fitting (non-adhesion) type damper wherein a vulcanized and molded rubber elastic body is press-fitted between a hub and a inertia mass body; and so on.
In a fitting type damper, a polymer elastic body for connecting a hub and a inertia mass body to each other is generally fitted in a compressed state. Therefore, the fitting type damper is known in that a process thereof is simpler and the durability thereof is higher than an adhesion type damper. On the other hand, when high load is applied to the fitting type damper, slipping in a rotary direction is often caused between the hub formed by metal parts and the rubber elastic body or between their inertia mass body formed by metal parts and the rubber elastic body.
Recently, therefore, for the fitting type damper the followings have been suggested to prevent this slip and to increase (improve) slipping torque: (5) a method of subjecting a fitting surface of a hub or a inertia mass body to shot blast treatment; (6) a method of giving adhesiveness to a rubber elastic body itself; (7) and a method of interposing polymethylene polyphenyl polyisocyanate on an interface between a hub and a rubber elastic body or between a inertia mass body and a rubber elastic body.
As a damper for realizing high durability and high slipping torque, there is a damper which is a fitting and adhesive type. The process of this damper comprises: a first step of applying an adhesive agent to respective surfaces of a hub and/or a inertia mass body so as to face a rubber; a second step of drying the applied adhesive agent; a third step of applying press-fitting liquid such as oil onto the dried adhesive agent; a fourth step of press-fitting a another vulcanized rubber between the hub and the inertia mass body; a fifth step of removing an excess amount of press-fitting liquid; and a sixth step of heating the assembled damper to adhere the hub and/or the inertia mass body to the another rubber.
Japanese Patent Laid-open No. 2-85543 discloses a structure in which a inertia mass body and a rubber elastic body are jointed with a silane type adhesive agent to improve heat resistance of the rubber elastic body for use of a dynamic damper. In Examples thereof, as examples of the rubber elastic body having heat resistance, an ethylene acrylic rubber and acrylonitril rubber are described, and as an example of the silane type adhesive agent, Y-4310 (which is trade name and is made by Lord Corporation) is described.
About a conventional fitting type damper subjected to shot blast treatment, the process thereof is simple but high slipping torque cannot be obtained.
About the conventional fitting type damper which has adhesiveness on surfaces of the rubber elastic body thereof, durability thereof is reduced and the process thereof is complicated. Moreover, press-fitting of conventional fitting type damper is difficult.
About the conventional fitting type damper in which polymethylene polyphenyl polyisocyanate is interposed, the following steps are necessary to make fitting easy: an applying step of applying press-fitting oil to a fitting surface of a hub or a inertia mass body and a washing step of removing this press-fitting oil after being fitted. Therefore, number of the process steps increases. Since the conventional fitting type damper has toxicity, problems about safety thereof arise, so that cost of manufacturing the damper rises.
About the conventional post-adhesion type damper obtained by applying an adhesive agent to a hub and a massive body and by press-fitting another vulcanized and molded rubber after carrying out heating and adhesion, the step of applying and drying the adhesive agent and the washing step of removing press-fitting oil are necessary. Therefore, number of the process steps increases. When the another rubber is press-fitted, by friction between a surface of the another rubber and an adhesive agent layer formed on a surface of metal fittings for fixing the another rubber, the adhesive agent layer may be partially sliced off, so that adhesion unevenness is easily caused.
Accordingly, the conventional fitting type dampers have above-mentioned various drawbacks.
An object of the present invention is to provide a fitting type damper making it possible to increase slipping torque highly, and in particular a fitting type damper capable of having a large slipping torque not only when the damper is new but also after both a heat aging test and a durability test are performed, and to provide a process of the fitting type damper.